TC Works Spark 1.5

The Browser View contains a waveform‑editing window (below) plus file‑management and playlist subwindows (top left and right respectively).

Paul White checks out TC Works' Spark, a Swiss Army knife of a Mac editor that takes an entirely new approach to the use of VST plug‑ins. It also offers sampler support and MP3 file creation, and its effects section can even run within other VST‑ and MAS‑compatible software.

TC's Spark is a Mac‑only stereo editing package which also includes a comprehensive effects matrix that works with standard VST plug‑ins. To run it, you'll need a 166MHz Power Mac 604 or better and you should be running Mac OS 8.1 or later. The majority of my testing was done using a modest beige 266MHz G3. Spark also has the ability to produce MP3‑coded audio files, of which more later, though its normal currency is AIFF‑, SDII‑ and WAV‑format files. You can work at 24‑bit, 96kHz if you want to, and there is provision to dither down to a lower resolution at the end of the processing chain.

Spark has no dongles or key disks. Instead, you install directly from CD and the software generates a unique 'challenge' based on your hardware. You can email or fax this challenge to TC Works and the code you get back authorises your machine. If you accidentally trash Spark, just reinstall it and enter your code again. However, if you need to move Spark to another computer, you'll need to call TC again to obtain a new code as this will be different for every computer. If you want to use Spark on different computers, then you could install it on an external drive and authorise that.

When you first install the software, it will run for 21 days without being authorised, so you don't have to worry about not being able to use Spark straight out of the box. The software can work with Apple Sound Manager (for playback but not recording) or it will record and play back via suitable ASIO or Direct I/O‑compatible hardware. If your hardware isn't ASIO‑compatible, you can still get it to work by selecting ASIO Sound Manager. I used Pro Tools hardware running under Direct I/O for my tests.

User Interface

The Cut Editor, a new addition to version 1.5 of Spark, provides powerful features for manipulating the transitions between audio regions.

Spark is based around two main windows, known as the Browser View and the Master View. In the Browser View, there are three sub‑windows for waveform editing, audio file management and the playlist. Any audio recorded or imported into the session is shown in the file‑management window. As with most editors, regions are defined in the waveform editor before the regions are assembled in a playlist. Regions may be whole songs or sections of songs to be reassembled into a new arrangement.

Master View deals with metering, real‑time processing and mixing, and it's here that the FXmachine resides, in which you can set up a matrix of up to 4 x 5 VST plug‑ins with numerous routing options. This may seem like overkill for routine editing, but it's certainly very powerful when you want to indulge in a little sound design. The Master View section is itself usable as a VST and MAS plug‑in so that the entire effects matrix can be used inside another application, almost like a kind of VST macro or shell. This is the only way I know that you can use VST plug‑ins inside Digital Performer, but as I don't use Performer myself, I have no way of verifying how well this works [Audio Ease are just releasing their VST Wrapper, though, which does the same thing — Assistant Ed].

In addition to the main windows, there's also a floating transport window with all the usual play/stop/fast wind buttons plus looping, location readout and a multifunction wheel that can be used for scrubbing, varispeed or time‑stretching. The scrub function can be used either from Play or Pause mode depending on whether you want play to resume automatically after scrubbing or not.

There's also a small section to the left of the Transport window where most of the I/O hardware settings can be chosen. Here you can see the selected sample rate, a resampling indicator to show if you're using the real‑time sample‑rate conversion, and a setup dialogue box to address your audio I/O hardware settings. Strangely, though, the option to switch from internal to external digital sync is in the program's preferences rather than being grouped with the other parameters.

Using Spark

The FXmachine (top left) is a matrix supporting four chains of five VST plug‑ins; FXmachine setups can themselves be used as VST plug‑ins within the matrix. Though the included Native CL Master (bottom right) provides only single‑band dynamics processing, the signal can be split into multiple bands within the FXmachine to perform multi‑band compression and limiting.

When you first click the Record button, the transport window extends to show the level meters and additional info windows for file format, signal source and so on. Alternatively, you can import an existing audio file. The most convenient way to find your way around the file once it is recorded is to insert markers at points of interest, such as the starts and ends of songs, or sections of songs to be edited. Markers can be created automatically when recording individual audio segments or they may be positioned in the file afterwards using a Command 'M' keystroke. Once placed, markers may be dragged to a more precise location after you have zoomed in to the waveform display. They can also be dragged in the overview waveforms display, which is a mixed blessing as I found myself dragging them by accident when I was trying to select sections of audio. Unwanted markers may be dragged out of the waveform edit window to delete them.

You can find the right place in a file by 'rubber‑banding' a section in the overview waveform, which automatically scales the main waveform display so that the selected section fills the screen. There's a user option so that either the main waveform window shows the cursor position as set in the overview waveform or the window remains where you last left it until you select a new section in the overview. My preference is generally for it to follow the cursor location; typing Shift 'F' engages this mode.

Once you've placed your markers, double‑clicking between any two markers selects that section of audio, which may then be saved as a region and named. New regions appear in the file‑management window. I find using markers more accurate than selecting the audio by clicking and dragging, as you can position the markers at a sensible zoom resolution for greater accuracy. Even then it doesn't matter if the selection isn't entirely accurate, as the region start and end points may be tweaked later by dragging in the waveform window or nudging in the Cut edit, accessed from the playlist. I would have appreciated a way to lock regions' start and end points to save them from accidental adjustment, and I understand this is under consideration for a future upgrade. Full horizontal and vertical zooming facilities are provided for the waveform display and a number of preset options may also be selected at the bottom right‑hand corner of the screen.

Creating regions is obviously a non‑destructive process, but Spark allows you to do destructive things such as silencing unwanted sections, cutting, pasting, moving and so on. There's also a drawing tool that can sometimes be useful for sorting out click problems by drawing in a 'best guess' of the corrupted section. In all instances where a destructive edit is carried out, the audio file needs to be updated. The way this works is that the first time you do a destructive edit, a revised version of the entire file is saved. From then on, the file isn't actually updated again until you do a Save, so if you want to get several edits under your belt before having to wait for the file to update, that's the way to do it.

The update time can be significant if you're working with an album‑length file, though single songs seem to take only half a minute or so. One slight annoyance is that the entire overview waveform also updates after each edit, which wastes time. What I'd like to see in future is a system that only updates the section of overview you've changed, which should be a lot faster. TC Works are aware of these criticisms and plan to address them as soon as is practical, but for now it's something you have to live with.

All the usual normalise, change gain, fade‑in/out and silence functions are supported alongside phase invert, DC offset removal, draw and erase (you have to zoom in close to activate these last two), but you can also do off‑line sample‑rate conversion, time‑stretching and varispeed, which makes the program useful for sound design and sample editing as well as track editing and mastering. There's a choice of curve types for the fades, though one function no audio editor seems to support is a fade option that can fade from, say, 10dB of attenuation to 0dB. Better still, a draggable level envelope system, as used in most audio sequencers and in Emagic's Waveburner, could be useful for fine‑tuning level changes within a song.

There is the option to work without the safety net of the undo function, in which case updates are made directly to original file, but there's no going back if you don't like it. A dialogue box asks you to confirm the edit, but you can't actually audition it before confirming. Even in this mode, you still have to wait for the entire overview waveform to be redrawn after each edit.

A potentially interesting feature I haven't noticed before on a program of this type is the facility to import audio directly from an Akai‑format CD‑ROM. However, this has to be done from a SCSI drive — you can't import from an Akai disc via the internal IDE CD‑ROM drives used on more recent Macs. Material from standard audio CDs can also be imported via Apple's QuickTime. When importing QuickTime movies, Spark automatically extracts the audio, allowing you to work on it separately; then, when you export it as QuickTime, it's merged back with the original movie. Any audio format supported by QuickTime can be used.

Cut Editor

The Cut Editor is new in version 1.5 of Spark, and is a feature that elevates it to the ranks of serious audio editor. Here you can view the transitions between playlist regions, apply various types of crossfades, butt edits or pauses and nudge the region boundaries in user‑definable increments. Visually, the editor is similar to the one in BIAS Peak, though Spark's allows you to audition two region boundaries (three regions) at once, allowing short edits, such as inserted single notes, to be heard in context. The crossfade shape can be seen overlaid on the waveforms, and the horizontal scaling adjusts automatically to suit the current fade length. If you set up any fade types that you might need to use again, you can save them as user presets. Nudge values can be changed by clicking in a numeric window and typing in a new value in milliseconds. One neat option here is an Auto function that tries to find the best edit point within the range of the largest set nudge value. There's even a compare function so you can audition two versions of your edit to see which sounds most natural. Depending on your preference, Spark will either continue to loop around the edit points as you make adjustments, or you can have it play only when you ask it to.

The region boundary to be edited is selected graphically below the waveform display, and to facilitate both music and dialogue editing, two types of crossfade are supported: Extend and Overlay. Extend mode would normally be used for music, so that when the crossfade length is changed, the edit point remains in the same place — the material for the fade is taken from outside the region. In Overlay mode the region lengths remain fixed, so the timing between the two regions changes as the fade length is changed. Unlike some editors, Spark's crossfades are not held in RAM, so they can be made as long as needed without fear of running out of memory. You can also step through from one transition to the next in the Cut Editor, which makes moving through the edit list both fast and intuitive.

The Cut window may also be used to position track IDs for CD burning; although Spark can't burn CDs directly, it can create an image file that can be opened and burnt in the included version of Adaptec's Toast. IDs may be positioned at the start, centre or end of a crossfade for albums where tracks run into each other. Note that if you want to produce CDs that are Red Book‑compatible for use as production masters, you'll need to buy Adaptec's more highly specified (and highly recommended) Jam, which is also supported by Spark.

Master View

Opening the Master window from the Windows menu reveals a new page with faders, high‑resolution level meters and a useful phase‑correlation meter on the left. This latter monitors the phase relationships between the two channels and can give some insight into the stereo spread of the material, as well as identifying low‑frequency phase problems that might adversely affect vinyl cutting. As vinyl seems here to stay in the DJ market, this is a valuable feature, but it takes a little experience to interpret the meter readings.

The Master View also contains the FXmachine, a four‑wide, five‑long matrix (see above) in the main part of the page into which VST plug‑ins may be loaded. A whole bunch of VST plug‑ins come with Spark, some of which are designed for mastering while others are there to grunge, munge or otherwise 'unge' clean audio for sound‑design purposes. The selection includes very respectable limiter, compression and EQ plug‑ins that can be useful in mastering; though the included limiter and compressor are only single‑band plug‑ins, you can use the included Cut Filter plug‑in to split the signal into up to four frequency bands within the FXmachine matrix, and compress and limit each individually for multi‑band dynamics processing. The ability to split the signal like this and process each band individually also offers plentiful scope for imaginative sound‑design processing.

You can of course also use any VST plug‑ins you already own, and the only limit as to how many you can use at once is the horsepower of your computer. Even more amazingly, you can save a complete FXmachine setup and then use it anywhere you like as a single VST plug‑in, even inside the original FXmachine matrix. However, 'double nesting' is as far as you can go, and until computers get very much faster, you'll probably have to exercise restraint while doing even this.

It's also possible to process files while recording with up to two VST plug‑ins (or FXmachine setups), and plug‑ins can be applied off‑line. This allows you to apply any VST plug‑in to an individual region within a file.

Routing is taken care of automatically when you add plug‑ins — put them in a line and the audio runs through them in series, put several side‑by‑side following a single plug‑in and the output from the first plug‑in will be split to feed all those that follow. If you want to change the routing, you can drag plug‑ins to new locations and also create new 'through' links in place of an effect, so whether you're after separate parallel chains of effects or some weird series/parallel arrangement, you can probably get Spark to do it. A nice touch is that the boundary of the virtual box holding each plug‑in doubles as a level meter, and each block has input, output and mix level controls. All effects setups can be saved as user presets, and there's a CPU activity meter to let you know when you've run out of steam.

Impression

Spark is only on its second revision, so it's hardly surprising that there are still areas in which it could be improved, particularly the means by which destructive edits are handled. The areas that need attending to first are those related to selecting and locking regions, and something needs to be done to speed up the recalculation of the overview waveform, but the program is very stable and offers many powerful features. As it stands, Spark is acceptably fast if you're going to treat each song on an album as a separate file, but if you load in everything in one hit, you'll find that any destructive edits really slow you down. I'd also like to see an automatic smoothing algorithm like the one found in Sound Designer II that helps avoid clicks when you draw in a new section of waveform by low‑pass filtering the cycle of audio that's been changed.

Fortunately, my list of likes is longer than my list of dislikes, and when you consider that you also get a worthwhile bundle of VST plug‑ins, first‑rate sample‑rate conversion and a good‑quality MP3 file converter, it's obvious that Spark is very good value. The overall presentation of the program is slick with not too many obscure tools to choose from, and the Cut Editor is very well thought out. Audio scrubbing works nicely for locating tricky edit points, and being able to move around material in the playlist freely using a progress slider makes auditioning transitions very fast.

As you might expect, the real‑time sample‑rate conversion, varispeed and pitch‑shifting aren't as good as their off‑line equivalents, also provided by Spark, though I have to say I was rather disappointed that there was no preview mode for time‑stretch — you have to make a best guess at the settings, do the job, then undo it if it isn't right. My attempts at both real‑time and off‑line time‑stretching tended to sound rather 'lumpy'. On the other hand, the off‑line sample‑rate conversion is done to a very high standard, with an extremely low level of aliasing.

The FXmachine is immensely flexible for sound‑design work, including the creation and manipulation of samples, and to this end, the built‑in sampler support is also welcome. The way it can use FXmachine presets inside itself is also very clever.

On the whole, the program is easy to use, with a relatively painless learning curve, though there are some functions that can only be accessed via key commands. Fortunately, the program comes with a separate set of key commands on a tear‑out card, so it might be nice to get that laminated at the local print shop. As it stands in version 1.5, Spark is a more than effective jack of all trades with some remarkable features, but it needs more work before it becomes an effective tool for handling long files. As it stands, I'd be inclined to work on songs as individual files, then assemble the finished songs using Jam's playlist. However, having seen how much the program has been developed since its inception last year, I'm expecting to see significant further evolution before very long.